Molded vinyl siding panels used to cover building exterior walls, particularly residential buildings, are well known in the prior art. Typically, 12 foot long elongated panels are attached in interlocking rows to the building exterior wall. Further typically, the panels are attached to the exterior wall using nails. Each individual siding panel is typically provided as a single-piece, unitary component having a body made to resemble two overlapping standard wooden exterior wall planks. An upper end of the siding panel is typically provided with a hem by which the panel is attached to the underlying wall. The hem may be of a single layer, or may be folded back upon itself to provide double layers. The hem is preferably provided with a plurality of apertures, each aperture sized and shaped to receive a nail. Typically, an outwardly projecting locking tab is provided adjacent to the hem, and connects the hem to the body. It is further known to provide an arcuately-shaped flange at a lower end of each panel. The flange is sized and shaped to interlock with the locking tab. Thus, the exterior wall may be covered by multiple rows of identical, interlocking siding panels, each panel being fixedly attached to the wall at the hem, and each panel also being connected by that panel's flange to a lower panel's locking tab and to an upper panel's flange by that panel's locking tab.
The connection between a first panel's locking tab and a second panel's flange is typically close fitting. Further, the flange is typically relatively flexible. In the prior art siding panels, the connection between a first panel's locking tab and a second panel's flange can be relatively easily disturbed, causing the two to separate. For example, the inventor of the present invention has determined that thermal effects, such as shrinkage in the underlying structure (such as floor joints) or lateral wind can cause separation. It is a common problem for the relatively close fitting conventional flange-locking tab connection to be unable to accommodate significant differential lateral (up and down) movement between joining panels, leading to the panels becoming disconnected. The resulting gap provides an entry path for rain and ice, increases the potential for damage to the building, and has a negative visual impact on the house. Repairs can be time-consuming and costly, since it typically involves removing 3 to 6 rows of panels above the separated panel. The panels are then loosely re-attached. The repair cost is typically in the range of $300 to $700.
The inventor has determined that separation of siding panels is particularly prevalent in two areas. The first area is along the floor joist area. This is due to shrinkage that occurs over the first few months to a couple of years in the underlying wood structure. The second area is where the siding panels meet an angled roof. The angular pitch of the roof tends to cause the ends of the panels tends to bend upward, causing buckling or warping of the panels. Currently,the only solution is to remove and replace siding panels when warpage or separation occurs.
A need exists, therefore, for a siding panel providing greater structural flexibility and reduced potential for separation of adjoining installed panels.